γ-Oxygenation of α,β-Unsaturated Esters by Vinylogous O-Nitroso Mukaiyama Aldol Reaction
摘要:
A practical procedure has been developed for gamma-oxygenation of alpha,beta-unsaturated esters by a vinylogous O-nitroso Mukaiyama aldol reaction followed by a one-pot N-O bond heterolysis of the in situ generated gamma-aminoxy-alpha,beta-unsaturated esters.
Enolisation of αβ-unsaturated esters : regio- and geometrical control
作者:Donald W. Cameron、Mark G. Looney、Judy A. Pattermann
DOI:10.1016/0040-4039(95)01531-0
日期:1995.10
LDA-Mediated γ-deprotonation of simple αβ-unsaturatedesters occurs (Z)- to the ester group; silylation then leads to oxy butadienes with strong regio- and geometrical selectivity.
Synthesis of the C1-C11 Segment of Tedanolide via Vinylogous Mukaiyama Aldol Reaction
作者:Markus Kalesse、Jorma Hassfeld
DOI:10.1055/s-2002-35582
日期:——
The successful construction of complex natural products depends to a large extent on how efficiently key intermediates can be generated. Here we report our efforts towards the first total synthesis of tedanolide (1), employing Evans’ aldol methodology in combination with a vinylogous Mukaiyama aldol reaction (VMAR) and Sharpless’ asymmetric dihydroxylation. This protocol allows for rapid access to its numerous chiral centers.
Advances in the vinylogous Mukaiyama aldol reaction and its application to the synthesis of the C1 C7 subunit of oleandolide
作者:Jorma Hassfeld、Markus Kalesse
DOI:10.1016/s0040-4039(02)00993-0
日期:2002.7
The synthesis of a stereo pentade of the macrolide antibiotic oleandolide is reported. The C1C7 fragment resembles the analogous segment of Panek's totalsynthesis of oleandolide. The use of the vinylogous Mukaiyama aldol reaction shortens the route significantly and has the advantage of utilizing an easily accessible ketene acetal.
[reaction: see text]. The use of the Z-configured vinylogous silyl ketene acetals in Mukaiyamaaldolreactions is described. Isopropyl alcohol as scavanger and the use of tris(pentafluorophenyl)borane as the Lewisacid are required for obtaining the gamma-alkylated syn-product selectively. In cases of alpha-chiral aldehydes, Felkin-Anh selectivity was observed.
A One-Pot Non-Aldol-Aldol Vinylogous Mukaiyama Aldol Tandem Sequence for the Rapid Construction of Polyketide Frameworks
作者:Markus Kalesse、Nicola Rahn
DOI:10.1055/s-2005-863743
日期:——
The rapid assembly of polyketide segments remains one central task in the field of natural product synthesis. Besides the stereoselective assembly of carbon frameworks functional group transformations and protecting group manipulations have to be optimized in order to streamline organic synthesis. The activated aldehyde derived from Jung’s non aldol-aldol method serves as an intermediate for the subsequent vinylogous Mukaiyama aldol reaction.